Method and an apparatus for measuring positions of contact elements of an electronic component

Abstract

A method and an apparatus for measuring respective positions of a set of N contact elements of an electronic component. A first and a second light path are created by a first and a second light beam which have different viewing angles. Both the first and the second light path can selectively be opened and both end into the image plane of a single camera. The positions being determined by using the first and second image produced by the first and second light beam respectively.

The invention claimed is: 
     
       1. An apparatus for inspection of an electronic component disposed in a measurement plane, comprising:
 at least one light source provided for generating substantially homogeneous light and illuminating said measurement plane; 
 a camera; 
 a first light path between said camera and said measurement plane, said first light path having a first section between said measurement plane and a first optical element and a second section between said first optical element and a second optical element, said first section of said first light path being substantially perpendicular to said measurement plane; and 
 a second light path between said camera and said measurement plane, said second light path having a first section between said measurement plane and a third optical element and a second section between said third optical element and a fourth optical element 
 wherein said at least one light source comprises first and second light sources to produce light in non-overlapping wavelength ranges. 
 
     
     
       2. The apparatus of  claim 1  further comprising means for subsequently switching on/off said first and second light sources. 
     
     
       3. The apparatus of anyone of  claims 1  or  2  wherein said second optical element is a dichroic mirror. 
     
     
       4. The apparatus of anyone of  claims 1  or  2  further comprising shutters for selectively opening and closing said first and second light paths. 
     
     
       5. The apparatus of anyone of  claims 1  or  2  wherein at least one of said second, third and fourth optical elements is a semi-transparent mirror. 
     
     
       6. A method of inspecting an electronic component having a set of contact elements disposed in a measurement plane, comprising:
 illuminating said measurement plane by means of a substantially homogeneous first and second light source; 
 forming a first light path between a camera and said measurement plane, said first light path having a first section between said measurement plane and a first optical element and a second section between said first optical element and a second optical element, said first section of said first light path being substantially perpendicular to said measurement plane; and 
 forming a second light path between said camera and said measurement plane, said second light path having a first section between said measurement plane and a third optical element and a second section between said third optical element and a fourth optical element; 
 forming a first image of said electronic component by means of said camera and by selectively opening said first light path; 
 forming a second image of said electronic component by means of said camera and by selectively opening said second light path; and 
 measuring a position of said contact elements of said electronic component by using said first and second image. 
 
     
     
       7. The method of  claim 6  wherein said first and second light source produce light with non-overlapping wavelength ranges. 
     
     
       8. The method of anyone of  claims 6  or  7 , wherein said first and second light path have a substantially equal average optical length. 
     
     
       9. The method of anyone of  claims 6  or  7 , wherein said first light source illuminates said measurement plane at an incident angle of at most 20.